Test a new spacecraft material

Being in space is not at all like being on Earth. It's usually very hot or very cold. There's no air. There's very little gravity. And the radiation is terrible!

Suppose you are a very smart spacecraft engineer. You have invented a new material to use for the fuel tanks on the spacecraft. But before you send your new material into the harsh environment of space, you must test it on Earth in a space-like situation.

Please get an adult to help you with this activity, because you will be heating and pouring boiling hot water!

To test this "new material" (which you have made in the shape of a soft drink can!) you will need:

An empty aluminum soft drink can

A medium-sized balloon

A fat rubber-band of a size to wrap once tightly around the top of the can

1/4 cup boiling water

Cut the top off the balloon.

Twist the pop-top off the can and carefully pour the boiling water into the can.

Being careful not to burn yourself on the hot can, stretch the balloon over the top of the can and secure around the rim with the rubber band. You don't want it to pop off or leak air.

Now watch.

What happens first? What happens after the water inside starts to cool? Keep checking the can every few minutes until it is completely cool.

Does this experiment tell you how good the material will be for making spacecraft fuel tanks?

How would this material work if the spacecraft were to be dropped into the very thick and high-pressure atmosphere of a planet like Jupiter?

Will this material be good for going into space?

What makes the can collapse?

The can collapses because you have made a partial vacuum inside the can. This means the air inside the can is thinner (less dense) than the air outside the can.

The vacuum in the soda can in this experiment is not much like the vacuum of space. Your soda can had less air in it than the same volume outside the can. But a true vacuum is a space with absolutely nothing in it—not even a single molecule of air!

As you can see from your test, a container made of this material bends and wrinkles when the air outside pushes harder than the air inside.

With spacecraft fuel tanks, the vacuum is on the outside, rather than the inside. So to properly test the fuel tanks on the ground you need to be able to create a vacuum outside of them. This is very hard to do in your kitchen! You need a vacuum test chamber—too expensive for the average home!

Engineers first test new spacecraft technologies in laboratories on Earth that try to copy conditions in space. But even these space labs can't exactly copy the conditions in space.

Engineers and scientists invent new technologies every day. Some of these inventions help to make the spacecraft smaller and lighter, or faster and more fuel-efficient, or easier to operate from Earth. Some of these inventions help scientists make better measurements of conditions in space or take better pictures of Earth from space. Some make it possible to detect the tiniest changes in the position or brightness of a distant star.

Hot air is thinner and lighter than cool air. When you seal the can, the air inside is hot. That means there are fewer molecules of air inside the can than there would be if the air were cool.

As the air inside the can cools, it pushes less hard against the inside of the can than the air outside the can is pushing. We created a partial vacuum in the can to see how well the material holds up when the pressure on the outside is greater than the pressure on the inside. Obviously not very well!

Hot air molecules have more energy than cool air molecules. They zoom around faster, bump into each other more, and knock each other farther apart. Hence, the hot air inside the can is thinner (less dense).

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Hot air is thinner and lighter than cool air. When you seal the can, the air inside is hot. That means there are fewer molecules of air inside the can than there would be if the air were cool.

As the air inside the can cools, it pushes less hard against the inside of the can than the air outside the can is pushing. We created a partial vacuum in the can to see how well the material holds up when the pressure on the outside is greater than the pressure on the inside. Obviously not very well!

Hot air molecules have more energy than cool air molecules. They zoom around faster, bump into each other more, and knock each other farther apart. Hence, the hot air inside the can is thinner (less dense).